docs(Select): fix double role=option in Item examples

[johnleider]

Closes #738

The Select compound and Item @example blocks spread slot attrs onto an inner <div> inside a non-renderless Select.Item. The Item already binds those attrs (role="option", onClick) on its own Atom, so the documented usage rendered listbox > div[role=option] > div[role=option] — axe aria-required-parent (critical) — and double-fired the click handler. Fixed by putting content directly in the slot; the fixture and docs select examples already had the corrected shape.

Bug-family sweep

Checked every component binding slotProps.attrs on a non-renderless Atom for the same @example defect:

Same defect, fixed:

• Combobox — both barrel @examples (compound + Item) had the identical inner-div spread; corrected the same way (Item highlight styling moved to a data-[highlighted] class on the component)
• Treeview — Cue/Checkbox/Indicator/SelectAll @examples spread attrs without renderless; added renderless (matches the docs example precedent). Same fix for Treeview.Cue in apps/docs treeview basic.vue
• Radio — RadioGroup slot @example duplicated role="radiogroup"; RadioRoot slot @example spread attrs and re-bound select alongside attrs.onClick (triple-fire). Added renderless, dropped the redundant handler

Checked clean: Select/Combobox fixtures and all select/combobox docs examples (already corrected shape), Selection/Single/Group examples (pure context providers, no Atom), Presence (renderless by nature), Rating/Avatar/Image docs examples (already renderless).

Out of scope per issue: Select.Activator button-name (#613/#635) and the accessible-name mechanism (#610).

Verification

• vitest --project v0:browser — a11y sweep + Select: 152 passed
• pnpm typecheck — green

[github-actions]

✅ Changeset found — this change will be included in the next release. Thanks!